Section 62 — Mistake of fact and knowledge for aggravation
English translation
As to any fact which, if it truly existed, would make the act not an offence, or would relieve the doer from punishment, or would reduce the punishment: even though that fact does not truly exist, if the doer mistakenly believes it to exist, the doer shall accordingly be without guilt, or be exempt from punishment, or receive a reduced punishment, as the case may be.
If such ignorance of fact as mentioned in the first paragraph arose from the doer's negligence, the doer shall be liable for negligence, in a case where the law specifically provides that the doer shall be punished even for an act committed through negligence.
A person who is to receive a heavier punishment by reason of any fact must have known that fact.
This English translation is provided for reference only and has not yet been firm-verified — always rely on the Thai original.
Firm annotation
Section 62 governs mistake of fact and completes the intention framework of Sections 59 to 61 in Book 1. Paragraph one gives effect to an honest mistaken belief in a favourable fact, so the doer is judged on the facts as believed, whether that removes guilt, exempts from punishment, or mitigates. Paragraph two preserves negligence liability where the mistake itself was negligent and the offence is punishable when committed negligently. Paragraph three states the key aggravation rule: a heavier penalty tied to a fact (such as the victim's status) applies only where the doer knew that fact, which is why status-based enhancements do not automatically follow from Sections 60 and 61. The provision is central to justification and excuse defences, including putative self-defence.
Why this matters in practice
Section 62 is the anchor for defences built on what the accused honestly believed at the time, including putative self-defence and honest mistaken consent, because the accused is judged on the facts as believed rather than as they were. The trade-off is paragraph two: if the mistake was careless, a negligence charge may still stand where the offence permits. On the prosecution side, paragraph three limits aggravation, an enhanced penalty resting on a fact such as the victim's status requires proof that the accused knew that fact. Framing exactly what the accused believed, and what they knew, is often decisive, so specific legal advice on the mistaken-belief evidence is valuable.
Supreme Court decisions interpreting this section
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Supreme Court Judgment No. 6876/2568 (2025)
Under Section 62 paragraph three, a defendant can be punished more heavily for killing an ascendant only if he knew that the person attacked was his ascendant.
Although the defendant could not escape intent to kill despite mistaking the victim's identity under Section 61, the Court held that the heavier penalty for an offence against an ascendant applies under Section 62 paragraph three only where the doer knew that aggravating fact.
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Supreme Court Judgment No. 2936/2564 (2021)
A fact that would relieve a doer from a heavier punishment under Section 62 paragraph three is not an element of the offence, so the prosecution need not plead it in the charge.
The Court held that the wording the defendants relied on was not an element of the aggravated assault offence but a matter that might relieve them from heavier punishment under Section 62 paragraph three. Accordingly the prosecution was not required to plead it, and charging that the victims were police officers acting in their duty was sufficient.
Curated decisions with case numbers verified against the Supreme Court database. English renderings are the firm's editorial translation for study.
Frequently asked questions
What is putative self-defence under Section 62?
If a person honestly but mistakenly believes facts that, if true, would justify self-defence, Section 62 lets the act be judged on the believed facts, so it may be treated as lawful defence. If the mistaken belief was negligent, a negligence charge may still apply where the law allows.
Does a heavier penalty for a victim's status apply automatically?
No. Section 62 paragraph three requires that a person to receive a heavier punishment by reason of a fact, such as the victim's status, must have known that fact.